It's the smoke part, and all the other stuff in ciggies that are bad for you. BTW, smoking tobacco grown in soils that contain uranium, which are actually fairly common, can release really bad raioactive stuff into your lungs.
Maybe the tobacco guys should sell it in pill form.
"OK men, ingest'em if you got'em."
There are enourmous benefits to nicotine - so much so, your brain actually manufactures it. Shhhhhh - don't tell the smoke nazis.